1. Field of the Invention
This invention relates to semiconductor device parts for use in a plastic packaged high-power semiconductor device and the like, and, more particularly, to semiconductor device parts comprising external electrode terminals and a terminal supporting body which is a portion of a package of the semiconductor device.
2. Description of the Related Art
FIG. 1A is a plan view showing the outer appearance of a plastic packaged high-power semiconductor device (G-TR Module) in general, and FIGS. 1B and 1C are partial cross-sectional front and side views, respectively, of the semiconductor device shown in FIG. 1A. In the device shown in FIGS. 1A to 1C, a semiconductor chip (not shown) is mounted on a circuit board 5 and electrically connected thereto by bonding wires. An electrode bed (not shown) for connecting electrodes to the external device is formed on the circuit board 5. A plastic terminal supporting body 1a and external electrode terminal parts 1b are formed integral with each other, constituting a terminal holder 1. The semiconductor device is formed as follows.
First, external electrode terminal parts 1b are placed in a plastic molding die, and plastic is injected into the die to form a terminal holder 1. Inner lead ends of the external electrode terminal parts 1b are adhered by solder 6 to the electrode bed on the circuit board 5. Next, a case 3, a heat radiating board 4, and the like are attached to the circuit board 5. To protect electronic circuits on the circuit board 5 from moisture, vibration, and the like, potting material 7 is injected into the case 3. Further, casting material 8 is injected on the potting material 7. In this way, a semiconductor device is completed as a product.
FIG. 2 is a perspective view showing the outer appearance of conventional semiconductor device parts (terminal holder 1). FIGS. 3A and 3B are partial cross-sectional front and side views, respectively, of the semiconductor device parts shown in FIG. 2. The external electrode terminal parts 1b for connecting an internal electrode on the circuit board 5 to an external device and the plastic terminal supporting body 1a are formed integral with each other by mean of plastic molding by use of a molding die. During the plastic molding, it is necessary to prevent plastic from being forced out through gaps between the molding die and the terminal parts 1b. For this purpose, the terminal parts 1b are fastened tightly by the molding die.
When the number of the external electrode terminal parts 1b are increased or when configurations of the terminal parts 1b are complicated, a complicated molding die must be used. As a result, it may be impossible to form the terminal parts 1b integral with the terminal supporting body 1a. In addition, due to the contacts between the terminal parts 1b and the molding die which occur when the terminal parts 1b are fastened by the molding die or due to the plastic injection pressure which is applied to the external electrode terminal parts 1b when the terminal parts 1b are molded, the external electrode terminal parts 1b tend to be deformed. When deformed defective terminal parts 1b are adhered to the circuit board 5 by a solder 6, the inner lead end 1b-1 of such defective terminal parts 1b cannot be perfectly adhered to the electrode bed. Thus, the defective terminal parts 1b-1 cannot be practically used. Since such defective terminal parts 1b lower the molding yield, the cost of manufacturing the terminal holder is inevitably increased.